Functions of PC Communicator: PC-to- FOMA IP Videophone Technology

Transcription

1 Functions of PC Communicator: PC-to- IP Videophone Technology Hideaki Takeda, Dai Ando, Sumitaka Sakauchi, Shigehiko Onishi, and Hirohisa Jozawa Abstract This article describes the point-to-point communication functions of the PC Communicator Internet protocol (IP) videophone/videoconferencing system developed by NTT Cyber Solutions Laboratories. The PC Communicator provides voice-over-ip telephony between a personal computer (PC) and various types of terminals such as another PC, PSTN (public switched telephone ) phone, cellular phone, or PHS (personal handy-phone system) phone. It also provides IP videophone connections between a PC and a or.phone Personal V phone from NTT DoCoMo and NTT Communications, respectively. 1. PC communicator NTT Laboratories and NTT Resonant Inc. have developed the PC Communicator (PCC), an Internet videophone/videoconferencing system that conforms to *1 (session initiation protocol). PCC is the NTT Group s first wholesale type service *2. It is being provided to NTT Communications Corp. by NTT Resonant Inc. as.phone Business V [1]. Commercial services began in March of this year and were upgraded at the end of May. PCC handles both point-to-point and multipoint calls among personal computers (PCs) and phone terminals, both fixed-line and mobile ones. A detailed explanation of multipoint calls is given in the third article in this Special Feature Videoconferencing Technology for High-quality PC Multipoint Connections [2]. Here, we explain the point-to-point communication functions of the PCC. 2. PCC system configuration PCC is integrated with a video communication service to form the PCC system. This comprises several NTT Cyber Solutions Laboratories Yokosuka-shi, , Japan takeda.hideaki@lab.ntt.co.jp s, a gateway (-GW), a public switched telephone gateway (PSTN- GW), and client software that runs on a Windows personal computer (Fig. 1). The s include a that administers call, a presence that provides a presence service that indicates whether or not a user is online and other such user information, an instant messaging service, and a multipoint videoconferencing that provides a videoconferencing service. The (called Type1-CA(SS)), presence (called Type1- CA(PS)), and PSTN-GW were developed by NTT Network Service Systems Laboratories. The technology that supports the PCC is explained in detail in the fourth article in this Special Feature Network Technology to Support PC Communication Services [3]. 3. PCC functions The functions of PCC are listed in Table 1. This *1 : An IETF (internet engineering task force) standard protocol for establishing sessions for telephony, chatting, etc. between terminals on an IP. *2 Wholesale service: A form of service in which a company uses the services and facilities of a service wholesaler to provide services to others. 18 NTT Technical Review

2 Network of company receiving the wholesale service (NTT Communications) Presence Network of company providing the wholesale service (NTT Resonant) Presence Multipoint videoconference PSTN-GW -GW IWE PDC terminal hardware phone (OCN.Phone, etc.) PCC client (.Phone Business V client) software phone (.Phone Personal,.Phone Personal V client) PSTN PDC terminal International telephone Subscriber telephone PHS PHS terminal PDC: personal digital cellular phone Fig. 1. PCC system and configuration. Table 1. Functions of PCC. Point-to point communication Multipoint communication Voice phone Videophone Instant messaging (IM) Active member list (presence) Address book Call history Access list Whiteboard File transfer Videoconferencing Videoconference chat Videoconference materials sharing Provides voice calls to analog phones, IP phones, cellular phones, etc. Provides video and voice communication between PCC terminals, between PCC and.phone Personal (V) terminals, and between PCC and terminals Provides point-to-point text-based conversation Displays log-in status (presence) and history Stores addresses and other user information (calls can also be made from the address book) Saves the history of incoming and outgoing telephone, videophone, IM, and videoconference calls (calls can also be initiated from the history) Assigns of telephone and videophone calls and incoming instant messages and presence queries Provides a point-to-point text and diagram sharing function Provides point-to-point file transfer Provides multipoint videoconference Enables text messaging among participants Shares materials, whiteboards, and applications among videoconference participants section describes the main functions used in the point-to-point communication. (1) Voice phone function The PCC client conforms to and contains a stack *3 developed by NTT Network Service Systems Laboratories. In addition, an audio echo and noise canceller developed by NTT Cyber Space Laboratories reduces echoes and noise to ensure that the quality of voice calls is high. *3 stack: A software library that implements the communication protocol. Vol. 3 No. 10 Oct

3 Table 2. Services compatible with PCC (.Phone Business V). Service type Voice phone Videophone Connection type IP-IP Via PSTN-GW IP-IP Via -GW OCN.Phone OCN.Phone Office.Phone IP Centrex OCN provider IP phone (050 number) (connection is free of charge).phone Personal.Phone Personal V Other provider s IP phone (050 number) (connection is not free of charge) Ordinary phone Cellular phone (PDC,, and voice calls) PHS Ordinary telephone outside Japan (international call).phone Personal.Phone Personal V Destination The standard enables PCC to provide IP (Internet protocol) telephony between PCC clients and hardware/software phones connected to the s of the company providing customers with the wholesale service (e.g., OCN.Phone or.phone Personal) as well as between PCC clients (Fig. 1). The PCC supports connections to both hardware phones (OCN.Phone, OCN.Phone Office, the IP phones of OCN providers, etc.) and software phones (.Phone Personal and.phone Personal V) registered in the s of NTT Communications. Voice communication with analog phones, cellular phones (PDC (personal digital cellular) or ) and PHS terminals is also possible by connecting to the PSTN via the PSTN-GW. The services that are compatible with PCC are listed in Table 2. (2) Videophone function This function provides IP videophone communication between two PCC clients and between a PCC client and a terminal. Video data is compressed and decompressed by an MPEG-4 developed by NTT Cyber Space Laboratories to reduce the processing load while maintaining high video quality. Between PCC clients, communication with screen sizes of CIF (352 pixels 288 lines) or QCIF (176 pixels 144 lines) is possible. In addition, a function for VGA-size (640 pixels 480 lines) communication has also been implemented (but is not provided for commercial use). During communication, the image size can be changed and communication can also be switched over to voice-only mode. The videophone windows of the PCC are shown in Fig. 2. Video communication between PCC and terminals passes through the -GW. Smallscale -GWs for enterprises have been on the market for some time, but large-scale systems for communication carriers have recently been introduced to produce the world s first carrier service for videophone connections between PC and cellular phone terminals. The function for videophone connections with terminals, which is another major feature of the PCC, is described in detail in the next section. The PCC client can make videophone connections to both the.phone Personal and.phone Personal V clients of NTT Communications. Because MPEG-4 encoding parameters are exchanged between the sending and receiving terminals in addition to the specifications, mutual MPEG-4 video connections between different types of IP videophone terminals are implemented through combination with the SDP *4 (session description protocol) description specifications and interpretation method. To exchange video information, SDP only specifies the method for declaring the capabilities; the operations at the receiving terminal side are not specified at all. NTT Resonant Inc. has created common specifications for exchanging capability information for MPEG-4 connections between all the *4 SDP: An IETF standard protocol for the exchange of session content information. It describes the types of video and voice s and their parameters and is used for connection between terminals. 20 NTT Technical Review

4 Fig. 2. Example of videophone screen. terminals offered by companies in the NTT Group rather than just between the PCC client and.phone Personal V. We intend to work towards greater use of the common specifications among all of the companies in the NTT Group. (3) Active member list function This function indicates the presence of a person registered in the active member list. That is, it indicates whether the person is online or offline, engaged in a call, etc. (Fig. 3). A member can use the access list function to specify whether or not his/her presence can be accessed by others. If queries are blocked, no presence information is displayed. In addition to icons that indicate presence status, this function allows text messages to be entered in the presence field. (4) Whiteboard function This function enables text and diagrams to be shared with a specified party. It can display materials prepared in advance and lets users write or draw on top of them (Fig. 4). The user who initially activated the whiteboard has of the functions for creating, adding, or deleting shared screens (pages) and incorporating materials, but he/she can choose to pass over to the other user. The shared screen can also be saved as a bit map or in some other format. The PCC whiteboard can also be used independently when communication with another terminal is not Presence Online Friends Member Office My status Message Mr. Usami Ms. Ono Mr. Ikedo I ll see you on videophone Fig. 3. Screen showing the active member list. taking place. The call connection is made using /SIMPLE *5 via the presence. (5) File transfer function This function transfers files to a specified other party. In the same way as for the whiteboard function, *5 SIMPLE: An IETF standard protocol for the exchange of presence and message information. Vol. 3 No. 10 Oct

5 Map Here Fig. 4. Screen showing the whiteboard. (3G-324M) terminal -GW PCC client System H.324 Speaker Mic Multimedia signaling H.245 Display Camera Video MPEG-4 Audio AMR Resend H.223 MUX/ DMUX IWE converter PRI Main data Line termination H.223 MUX/ DMUX Call data AMR G.711 conversion H.245 SDP conversion call Video RTP Audio RTP RTP RTP Video RTP Audio RTP Audio capability Call Video MPEG-4 Audio G.711 SDP analysis Display Camera Mic Video Speakers capability H.324: ITU-T Recommendation. A multimedia communication system that uses the analog telephone. 3G-324M is a specification that is based on the H.324 mobile version H.324/M. H.223: ITU-T Recommendation. A low bit rate multimedia multiplexing and demultiplexing protocol. RTP: realtime transport protocol. An IETF standard protocol for realtime transfer of voice and video over a. H.245: ITU-T Recommendation. A procedure for performing format and protocol negotiation for calls between terminals. AMR: advanced multirate. A voice compression and encoding method for flexible variation of transfer rate according to line type and conditions. It is used for third-generation cellular phones based on W-CDMA (wireless code division multiple access). G.711: ITU-T Recommendation. The PCM (pulse code modulation) voice coding specification that is most widely used for IP phones. Fig. 5. connection system configuration. 22 NTT Technical Review

6 Table 3. Functions of -GW. Call processing conversion Transport conversion Media description conversion H. 324 (Q. 931) H. 223 RTP H. 245 SDP Voice transcoding AMR G. 711 Video transcoding None (MPEG-4 through) Q.931: ITU-T Recommendation. A protocol for establishing connections between terminals. it can also be used independently, whether or not a call is in progress. The call connection is also made via the presence. It is possible to transfer files directly (up to 100 Mbytes at a time) without an intermediate file. 4. connection service (1) Connection method The PCC uses Internet Protocol based on packet switching which differs fundamentally from s 64-kbit/s circuit switching, so a connection to either of them must go via a -GW. The system configuration for a connection is illustrated in Fig. 5. The -GW is connected by a leased line primary rate interface (PRI) to an NTT DoCoMo IWE (interworking equipment). The -GW converts between the specifications of the 3G-324M and IP phone standards. As shown in Table 3, media description conversion for call processing conversion, transport conversion, and information conversion between terminals and voice transcoding are performed. The MPEG-4 of the PCC also conforms to the specifications, so transcoding at the -GW is not necessary. Thus, the processing load on the -GW is reduced and the channel cost can also be reduced. The screen size for a connection is QCIF, which is the upper limit for the 3G-324M specifications. The specifications of the MPEG-4 encoder of terminals vary from manufacturer to manufacturer, but the PCC has demonstrated connectivity with all devices of the 2102V series and later (900i, 901i, and 700i). (2) Concept of use Videophone connections between PC and terminals make possible ubiquitous video communication that is unrestricted in time or space. A few examples of this are given below. Remote support and instruction from the office for company employees who are out of the office. Remote consultation between customers and a call center (e.g., explanation of how to use home appliances and solve problems) Remote monitoring to understand the situation at another place of business from the office or to check on conditions at home while away on business Broadcasting to the home or office the conditions at an exhibition or during a trip Distance learning while at home or traveling The fusion of the Internet and cellular phones is expected to increase the opportunities for video communication. 5. Future development We will continue to improve the functions of PCC and add new functions in response to customer needs and utilize NTT research results as well as technology on the market to increase the added value. References [1] (in Japanese). [2] H. Takeda, M. Moriuchi, T. Imaeda, S. Honda, and T. Yasuno, Videoconferencing Technology for High-quality PC Multipoint Connections, NTT Technical Review, Vol. 3, No. 10, pp , [3] Y. Yamanaka, S. Esaki, A. Shibata, S. Takada, and S. Seto, Network Technology to Support PC Communication Services, NTT Technical Review, Vol. 3, No. 10, pp , Vol. 3 No. 10 Oct

7 Hideaki Takeda Senior Research Engineer, Supervisor, Promotion Project 1, NTT Cyber Solutions Laboratories. He received the B.E. and M.E. degrees in electrical engineering from Hokkaido University, Sapporo, Hokkaido in 1979 and 1981, respectively. In 1983, he joined the Electrical Communication Laboratories of Nippon Telegraph and Telephone Public Corporation (now NTT), Kanagawa. He has been engaged in R&D of information systems. He is a member of the Information Processing Society of Japan. Shigehiko Onishi Manager, Visual Communications Division, NTT IT Corp. He received the B.E. and M.E. degrees in electrical & computer engineering from Yokohama National University, Yokohama, Kanagawa, in 1989 and 1991, respectively. He joined NTT LSI Laboratories in From 2000 to 2003, he was with ATR Spoken Language Translation Research Laboratories, Kyoto, Japan. From 2003 to 2005, he was engaged in research on video coding systems at NTT Cyber Space Laboratories. His research interests include audio/speech signal processing and image processing. He is a member of IEICE and ASJ. Dai Ando Research Engineer, Promotion Project 1, NTT Cyber Solutions Laboratories. He received the B.E. degree in information technology from Tohoku University, Sendai, Miyagi in In 1989, he joined NTT Human Interface Laboratories and has mainly been engaged in developing video communication systems. He is a member of the Institute of Electronics, Information and Communication Engineers (IEICE) of Japan. Hirohisa Jozawa Senior Manager, NTT Resonant Inc. He received the B.E. and M.E. degrees in electrical engineering from Waseda University, Tokyo, in 1987 and 1989, respectively. He joined NTT Human Interface Laboratories in 1989 and was engaged in R&D of video coding systems. He was a Senior Research Engineer, Supervisor of NTT Cyber Space Laboratories, and moved to NTT Resonant Inc. in He is a member of IEICE and the Institute of Image Information and Television Engineers of Japan. Sumitaka Sakauchi Associate Manager, NTT Advanced Technology Corporation. He received the B.S. degree in physics from Yamagata University, Yamagata in 1993, the M.S. degree in physics from Tohoku University, Sendai, Miyagi in 1995, and the Ph.D. degree in engineering from Tsukuba University, Tsukuba, Ibaraki in He joined NTT in Until 2005, he was engaged in R&D of acoustic echo cancellation and noise reduction as a Research Engineer, Media Processing Project, NTT Cyber Space Laboratories. He moved to the present position in He received the Best Paper Award from IEICE in He is a member of the Acoustical Society of Japan (ASJ) and IEICE. 24 NTT Technical Review